A). Field of the Invention
The present invention relates generally to a fine pattern forming method and a semiconductor device manufacturing method, and more particularly to a method of forming a micro pattern by exposing and developing a photosensitive resist film and a method of manufacturing a semiconductor device using micro patterns.
B) Description of the Related Art
Japanese Patent Laid-open Publication HEI-13-196355 discloses the technique of exposing and developing a resist film formed on an antireflection film made of organic material and thereafter etching the antireflection film by using mixture gas of Cl2, HBr, O2 and Ar. Japanese Patent Laid-open Publication HEI-10-98029 discloses a method of etching an antireflection film by using mixture gas of HBr and O2. While the antireflection film is etched, the surface layer of a resist pattern is also etched and the pattern shrinks. It is therefore possible to form a pattern finer than the resist pattern immediately after development.
With these methods, however, deformation of a protective film attached on the sidewalls of a resist pattern applies stress to the resist pattern or the resist resin is chemically reacted with halogen-based gas. Such stress to and chemical reaction with the resist pattern are not actualized if the pattern size is large. If the minimum size of a resist pattern after size reduction is in the order of 100 nm or smaller, a resist pattern itself may be deformed or fell out.
Japanese Patent Publication No. 2928391 discloses the technique of etching an organic antireflection film under a resist pattern by using mixture gas of Cl2, SO2 and O2 or mixture gas of SO2 and O2. If etching gas contains halogen gas such as Cl2, a resist pattern is inevitably damaged by chemical reaction.
Other related arts are disclosed in Japanese Patent Publication No. 2971443.